The present invention relates to a braking device for a two wheeled motor vehicle such as a motorcycle. More particularly, the present invention relates to a braking device for a motorcycle which can coordinate operation of a rear wheel braking mechanism with operation of a front wheel braking mechanism.
A braking device for a motorcycle, that is capable of detecting reduced rear-wheel load resulting from braking of the front wheel, and thereby preventing trouble with brake control due to the reduction of the rear-wheel load, is known. One example of such a device is disclosed in Japanese Laid-Open Patent No. 2002-29403.
The braking device described in Japanese Laid-Open Patent No. 2002-29403 monitors changes in a rear wheel speed, and detects a reduction of the rear-wheel load associated with front wheel braking, based on the changes in the wheel speed. For example, as shown in FIG. 15 of the present drawings, the conventional braking device determines that the rear-wheel load is reduced when the rear wheel speed changes so as to have small deceleration gradient in relation to the front wheel braking (see the line denoted as “conventional rear wheel speed” in FIG. 15).
However, in the braking device described in Japanese Laid-Open Patent No. 2002-29403, a brake system in which wheel braking mechanism on the front and rear wheels are not operated in conjunction with each other is a prerequisite. Thus, the reduction of the rear-wheel load during a front wheel braking operation cannot be accurately detected in a device adopting a brake system in which the front and rear wheel braking devices are operated in conjunction with each other by a braking operation of one of the front and rear wheels (CBS: COMBINED BRAKE SYSTEM, hereinafter referred to as a “CBS”), even if the foregoing conventional technology is applied thereto as is.
Specifically, in the case of the known system in which the front and rear wheel braking devices are not operated in conjunction with each other, when the rear-wheel load is reduced as a result of front wheel braking, the deceleration gradient of the rear wheel acted upon by no braking force changes to become smaller. However, in the case of the CBS, when the rear-wheel load is reduced during the front wheel side braking operation, the braking force effectively acts on the rear wheel to increase the deceleration gradient, contrary to the above case (see the line denoted as “CBS rear wheel speed” in FIG. 15). The change of the deceleration gradient increasing in the middle, as described above, is a change similar to an ordinary slip in braking. Thus, the reduction of the rear-wheel load during the front wheel side braking operation cannot be accurately detected, using the known devices.